“Umami” is a term commonly used to describe the taste impact of L-glutamate salts and certain nucleotides. Umami is the main taste in the Japanese stock called “dashi”, and in bouillon and other stocks. Glutamic acid is a major constituent of food proteins (plant and animal) such as those abundantly found in foods such as meat, poultry, seafood and vegetables. Two nucleotides that contribute most to the umami taste, GMP (guanosine monophosphate) and IMP (inosine monophosphate) are also present in many foods. By themselves these nucleotides do not typically give as powerful a flavour result as MSG (monosodium glutamate). However, due to a synergistic interaction with MSG, a pronounced enhancing effect can be observed if these nucleotides are used in combination with MSG.
The umami taste has characteristic qualities that differentiate it from other tastes. It has been convincingly shown that umami represents the fifth taste, in addition to the other four basic tastes sweet, acid, salt and bitter. The most common descriptors that are used to describe the umami taste include “savoury”, “meaty” and “broth-like”. “Umami” is literally translated as “delicious”.
As alternatives to MSG and 5′-nucleotides, other molecules have been proposed as (umami-like) taste modulating substances:
Organic acids like tartaric and succinic acid have been reported to exhibit taste enhancing properties (Ney [1971] Z. Lebensm. Unters. Forsch. 146: 141; Velisek et al. [1978] Nahrung 22: 735). Taste modifying properties have also been attributed to certain di- to octa-peptides (Yamasaki and Maekawa [1978] Agric. Biol. Chem. 42: 1761; Noguchi et al. [1975] J. Agric. Food Chem. 23: 49).
WO 97/04667 discloses tripeptides containing a hydrophobic amino acid residue and at least one acidic amino acid residue as well as N-lactoyl-X substances, wherein X represents an amino acid residue, as flavouring ingredients to impart savoury taste and increase the mouthfeel of foodstuffs. It is also disclosed that these peptides and derivatives can partly mimic organoleptic features of MSG.
EP-A 1 252 825 discloses flavouring compositions for imparting umami taste to food products comprising substances that are formed by the reaction of the primary or secondary amino group of an amino acid, peptide or protein with the carbonyl group of a reducing sugar. According to this document the most preferred substances are those wherein the amino acid residue is selected from glutamic acid or aspartic acid and the sugar residue is selected from fructose, glucose, maltose, lactose, galactose, rhamnose, xylose and mannose.
EP-A 1 356 744 discloses flavouring compositions containing N-acetylglycine and the use thereof for imparting umami taste to foodstuffs.
As described above umami taste and umami imparting substances contribute to the flavour of foodstuffs, especially in the savoury range.
In sweet and beverage products, further examples of the importance of the gustative dimension of flavourings have been reported. These examples include taste attributes such as bitterness, tingling and cooling-freshness.
Bitterness is an essential aspect of some food flavours, among which chocolate taste. Purine alkaloids, like theobromine and caffeine, as well as amino acids and peptides have been known for a long time as bitter substances. In British patent no. GB 1420909 it is disclosed that the bitter flavour of cocoa can be reproduced using a combination of a purine alkaloid and an amino acid or an oligopeptide which ‘produces a surprisingly more natural simultaneously bitter and astringent flavour note than either of these types of substances alone’.
Menthol, an important constituent of peppermint oil, has a strong impact on flavoured products not only because of its mint smell but also because it imparts a cooling and fresh taste. Next to mint flavoured products, it has been suggested to employ menthol in other types of flavour to impart a cool taste. US patent application no. US 2005013846 for example discloses how menthol and derivatives thereof can be used as flavouring in water continuous spreadable acidified food products to obtain table spreads exhibiting a fresh, cool taste impression.
Similarly, cinnamic aldehyde and eugenol, constituents of cinnamon oil, are used in flavouring composition for confectionary products, not only for their smell but also because they impart a warm and tingling taste. The oral pungency of cinnamic aldehyde was described as burning and tingling by Cliff M and Heymann H [Journal of Sensory Studies 7 (1992)279-290]. According to the same authors eugenol exhibits a long-lasting numbing effect. Cinnamon oil has been proposed as a taste improving flavouring. International patent application no. WO9006689 discloses that cinnamon oil, among other spice extracts, added to a minty flavour formulation, can be used to improve the long-lasting flavour of chewing-gum.
Although a lot of work has been focused on finding taste improving substances that are capable of imparting new exciting taste attributes, there still is a need for new taste improving substances, and in particular for taste improving substances that are suitable for use in both savoury and non-savoury applications.